Rotary connector

ABSTRACT

A rotary connector including a first housing rotatably connected to a second housing and forming an annular space therebetween, and a flexible cable wound within the annular spacing. According to a first aspect, the conductors of the flexible cable associated with an airbag circuit are spaced further apart than conductors for other circuits mounted on a steering wheel. A direct connector includes first terminals connected to the airbag conductors and second terminals connected to the other conductors. The first and second terminals are spaced apart and/or divided by a divider to prevent interference during assembly. In accordance with the second aspect, a locking member for preventing relative rotation of the first and second housings prior to assembly on a vehicle includes a cover portion for covering an open end of the direct connector.

This application is a division of application Ser. No. 08/401,598 filedMar. 9, 1995, now U.S. Pat. No. 5,562,466 issued Oct. 8, 1996.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotary connector for electricallyconnecting a pair of housings, which are coupled to each other in such amanner as to be relatively rotatable, through a flexible cable, and moreparticularly, to a rotary connector for use in connection of a pluralityof circuits mounted on a steering wheel of a vehicle including an airbag circuit and other circuits, such as a horn circuit or an automaticcruise control circuit.

2. Description of the Related Art

Rotary connectors of the above-described type generally include a pairof housings coupled to each other in such a manner as to be relativelyrotatable, and include a belt-like flexible cable accommodated in anannular space defined between the two housings. The two ends of theflexible cable are electrically connectable to an exterior of thehousings when the flexible cable is fixed to the two housings. Theflexible cable has a plurality of parallel conductors. A connector isconnected to the end of the portion of the flexible cable which extendsexternally from the housing. Such a connector is generally a specialconnector connected to the end of the portion of the flexible cablewhich extends externally from the housing over a predetermined length.An alternate connector connected to the end of the externally extendedportion of the flexible cable is the direct coupling type connectordisclosed in U.S. Pat. No. 5,230,713. This connector has a plurality ofterminals provided on the housing as connected to the conductors of theflexible cable.

The rotary connector arranged in the manner described above is assembledin a steering device of a vehicle and is used as electrical connectionmeans between various circuits, such as an air bag circuit or a horncircuit. In that case, one of the housings of the rotary connector isconnected to a steering column (a stator), while the other housing isconnected to a steering wheel (a rotor). The special connectors ordirect connectors connected to the two ends of the flexible cable areconnected to external connectors mounted in an air bag inflator or ahorn switch.

When a driver turns the steering wheel in either of the two directionswhile driving a vehicle, the housing mounted on the steering wheel turnsin the same direction as that of the steering wheel, winding orunwinding the flexible cable in the rotary connector depending on thedirection of turning of the steering wheel. In either state, electricalconnection between the rotor and the stator is maintained by theflexible cable of the rotary connector.

When the rotary connector is assembled in the steering device of avehicle, the flexible cable must be assembled in a state wherein it canbe wound or unwound by almost the same amount from a reference positionassociated with the neutral turning position of the steering wheel.

Hence, the rotary connector is provided with a locking mechanism formaintaining the two housings at the position until the rotary connectoris assembled in a steering device. Such a rotary connector is designedsuch that free turning of the two housings is impeded until the rotaryconnector is assembled in the steering device, by the locking membermounted relative to the two housings which have been positioned at theneutral turning position. The locking member is removed from the twohousings when one of the housings is fixed to the steering column.

In recent years, the number of circuit parts provided on the steeringwheel of a vehicle have known to increase. That is, there is anincreasing demand for providing, on the pad of a steering wheel, controlswitches for, for example, an automatic cruise control circuit or an airconditioner circuit, in addition to the air bag inflator and or the hornswitch. An increase in the number of circuits connected by the rotaryconnector inevitably increases the number of conductors of the flexiblecable. However, the space near the steering device is limited, and anincrease in the width of the flexible cable is thus restricted. As aresult, the electrical insulation distance between the conductors isreduced, and this makes insulation of the conductor used for an air bagmore important than the insulation for other conductors because a largeramount of current compare to that which flows in other conductors, flowsin the air bag conductor to actuate the air bag inflator.

However, in the case of the aforementioned direct connector, since theterminals are connected directly to the conductors in the connectorprovided on the housing by, for example, spot welding or soldering, adecrease in the pitch between the conductors, caused by an increase inthe number of conductors of the flexible cable, reduces the distancebetween the adjacent connecting portions, thus reducing the electricalinsulation distance. Thus, the direct connector is not suited forconnection of multiple circuits.

In view of the aforementioned problems of the pior art, an object of thepresent invention is to provide a rotary connector which is suitable foruse in connection of multiple circuits.

U.S. Pat. No. 5,230,713 discloses the direct coupling type rotaryconnector in which connectors connected to the two ends of the flexiblecable are provided on the housings so as to achieve direct connectionwith external devices, such as an air bag inflator. In such a rotaryconnector, since the connectors are formed integrally with the housings,electrical connection between the flexible cable and the externaldevices is obtained at the same time as the assembly of the rotaryconnector in the steering device, thus simplifying the connectionprocess between the rotary connector and the external devices.

However, in the direct coupling type direct connector, since a pluralityof terminals thereof are exposed from the housing, a cover member mustbe covered on the direct connector for the purpose of preventingdeformation of these terminals and enhancing the dust preventionproperty. Accordingly, in the assembly process of the rotary connector,the aforementioned locking member and the cover member must be mountedseparately, making the assembly operation complicated. Further, in theinspection process conducted after assembly of the rotary connector inthe steering device to check whether or not the rotary connector hasbeen accurately connected to the external devices, electricalcharacteristics are satisfied only if the cover member has been removedand the external devices have been connected to the direct connecter.Thus, if the locking member is left unremoved, it is impossible in thatinspection process to check whether or not the locking member has beenimproperly left connected to the rotary connector during assembly.

In view of the aforementioned problems of the prior art, a second objectof the present invention is to provide a rotary connector which preventsaccidental unremoval of a locking member.

SUMMARY OF THE INVENTION

To achieve the first object of the present invention, there is provideda rotary connector which comprises a pair of housings coupled to eachother in such a manner as to be relatively rotatable, and a belt-likeflexible cable wound in an annular space defined by the two housings,the flexible cable having a conductor for an air bag and anotherconductor parallel to the conductor. Two ends of each of the respectiveconductors of the flexible cable are electrically extended externallyfrom the housings. At least one of the two externally extending ends ofeach of the conductors being connected to a corresponding terminal of adirect connector provided on the housing. The direct connector has apartitioning wall for separating a terminal connected to the conductorfor the air bag from a terminal connected to the another conductor.

To achieve the first object of the present invention, there is furtherprovided a rotary connector which comprises a pair of housings coupledto each other in such a manner as to be relatively rotatable, and abelt-like flexible cable wound in an annular space defined by the twohousings, the flexible cable having conductors for an air bag and otherconductors parallel to the conductors. Two ends of each of therespective conductors of the flexible cable being electrically connectedto an external portion of the housings. At least one of the twoexternally extending ends of each of the conductors is connected to acorresponding terminal of a direct connector provided on the housing.The direct connector has a gap for separating terminals connected to theconductors for the air bag from terminals connected to the otherconductors. A space of the gap is set to a value larger than a pitch atwhich the terminals connected to the other conductors are arranged.

To achieve the second object of the present invention, there is provideda rotary connector which comprises a pair of housings coupled to eachother in such a manner as to be relatively rotatable, and a flexiblecable wound in a space of the two housings, the flexible cable having aplurality of parallel conductors. Two ends of the flexible cable areelectrically extended externally from the housings in such a statewherein the flexible cable is fixed to the housings. At least one of thetwo externally extending ends of the flexible cable is connected to anexternal device through a direct connector provided on the housing. Alocking member for prohibiting free rotation of the two housings isremovably mounted between the housings. A cover for covering the directconnector is formed integrally with the locking member.

According to a first aspect of the present invention provided to achievethe first object, the conductor of the flexible cable for the air bagand the other conductors thereof are connected to the correspondingterminals of the direct connector, respectively. The terminals of thedirect connector, connected to the conductor for the air bag, and theterminals connected to the other conductors of the flexible cable areseparated from each other by a partitioning wall or a gap.

According to a second aspect of the present invention provided toachieve the second object, since the locking member is mounted relativeto the two housings which have been positioned at a neutral turningposition in the rotary connector manufacturing process, the rotaryconnector which has been positioned at the neutral turning position canbe assembled in a steering device in a state wherein free turning of thetwo housings is prohibited by the locking member. In that case, sincethe cover for covering the direct connector provided on the housing isformed integrally with the locking member, mounting of the lockingmember offers protection of the direct connector. Thus, separate processof covering the direct connector with a covering member is eliminated.

In the process of assembling the rotary connector in the steeringdevice, when the locking member is removed from the two housings, thetwo housings are unlocked and at the same time the cover is removed fromthe direct connector, enabling the rotary connector to be electricallyconnected to external devices through the direct connector. In otherwords, the external devices can be connected to the direct connectoronly when the cover formed integrally with the locking member isremoved. Thus, by inspecting electrical connection between the rotaryconnector with the external devices after the rotary connector has beenassembled in the steering device, whether or not the locking member isremoved can be determined, thus eliminating production of defectivearticles due to an accidental failure to remove the locking member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view of a first embodiment of arotary connector according to the present invention;

FIG. 2 is a plan view of a flexible cable provided in the rotaryconnector of FIG. 1;

FIG. 3 is a perspective view of essential parts illustrating a connectedstate between a direct connector and the flexible cable provided in therotary connector of FIG. 1;

FIG. 4 is a perspective view of essential parts illustrating a connectedstate between a direct connector and a flexible cable which are providedin a second embodiment of the rotary connector according to the presentinvention;

FIG. 5 is a perspective view of essential parts illustrating a connectedstate between a direct connector and a flexible cable which are providedin a third embodiment of the rotary connector according to the presentinvention;

FIG. 6 is a perspective view of essential parts illustrating a connectedstate between a direct connector and a flexible cable which are providedin a fourth embodiment of the rotary connector according to the presentinvention;

FIG. 7 is a perspective view of a fifth embodiment of the rotaryconnector according to the present invention;

FIG. 8 is a vertical cross-sectional view illustrating a state wherein alocking member is mounted on the rotary connector of FIG. 7.

FIG. 9 is a perspective view of essential parts of a sixth embodiment ofthe rotary connector according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below withreference to the accompanying drawings.

FIG. 1 is a vertical cross-sectional view of a rotary connectoraccording to a first embodiment of the present invention. FIG. 2 is aplan view of a flexible cable provided in the rotary connector shown inFIG. 1. FIG. 3 is a perspective view of essential parts illustrating aconnected state of a direct connector provided in the rotary connectorshown in FIG. 1 and the flexible cable.

Referring first to FIG. 1, a first housing 1 made of a synthetic resinhas a disk-shaped bottom plate 2 and an outer cylindrical portion 3connected to an outer peripheral edge of the bottom plate 2. The bottomplate 2 has a center hole 4 formed at a center thereof. A second housing5, made of a synthetic resin, has a disk-shaped ceiling plate 6 and aninner cylindrical portion 7 connected to a central portion of theceiling plate 6. The inner cylindrical portion 7 has a shaft insertionhole 8. The first and second housings 1 and 5 are coupled to each otherin such a manner as to be rotatable relative to each other with theouter peripheral edge of the ceiling plate 6 being guided by the upperedge of the outer cylindrical portion 3 and the lower edge of the innercylindrical portion 7 being guided by the inner edge of the bottom plate2. A flexible cable 9 is housed in an annular space defined by thebottom plate 2 and outer cylindrical portion 3 of the first housing 1and the ceiling plate 6 and the inner cylindrical portion 7 of thesecond housing 5. The flexible cable 9 is wound in a spiral fashion inthe space. One end of the flexible cable 9 is led out from the firsthousing 1 in a state wherein it is fixed to the outer cylindricalportion 3. A special connector (not shown) is connected to a distal endof the portion of the flexible cable 9 which is led out from the firsthousing 1. The other end of the flexible cable 9 is led out of thesecond housing 5 through a direct connector 10.

As shown in FIG. 2, the flexible cable 9 is a belt-like flat cable inwhich a plurality of parallel conductor wires 11a through 11f arelaminated by a pair of insulating films 12. The conductors 11a and 11bare used for connection with an air bag circuit. The conductor wires 11cto 11f are used for connection with a horn circuit, an automatic cruisecontrol circuit or an air conditioner circuit. A current which flowsthrough the air bag circuit is the largest, so the spacing between theair bag conductors 11a and 11b is larger than the opening between theother conductor wires 11c to 11f. Further, very high connectionreliability is required for the air bag circuit, so a noble metalplating, such as gold plating, is provided only on the surface of theportion of the air bag conductors which is exposed from the insulatingfilms 12. A current which flows through the horn circuit is the secondlargest, so the conductor wire 11f located farthest from the air bagconductors 11a and 11b is used for the connection with the horn circuit.Further, a notch 9a is formed at one end portion of the flexible cable9, whereby the flexible cable 9 is divided into the air bag conductors11a and 11b and the other conductor wires 11c to 11f. The two parts arerespectively folded at folding lines A and B which lie at 45 degreeswith respect to the lateral direction of the flexible cable 9 so as toallow the flexible cable 9 to be directed toward the direct connector10.

As shown in FIG. 3, the direct connector 10 includes a protruding casing13 made of a synthetic resin and erected from the upper surface of theceiling plate 6, a plurality of terminals 14a to 14f disposed in theprotruding casing 13, and connecting plates 15 and 16 for connecting theterminals 14a to 14f with the conductor wires 11a to 11f. A partitioningwall 13a is formed integrally with the casing 13 at a central portionthereof to divide the terminals into the terminals 14a and 14b and theterminals 14c to 14f. The terminals 14a and 14b are also plated with anoble metal, such as gold. The terminals 14a and 14b are connected tothe air bag conductors 11a and 11b within the one connecting plate 15 bymeans of, for example, soldering or spot welding. Similarly, theterminals 14c to 14f are connected to the conductor wires 11c to 11fwithin the other connecting plate 16 by means of, for example, solderingor spot welding. The connecting plates 15 and 16 are fixed in theprotruding casing 13 by an adequate means, such as press fitting orsnap-fastening.

The operation of the rotary connector according to the first aspect ofthe present invention will now be discussed. In the followingdescription, the first housing 1 is used as a fixing member, while thesecond housing 5 is used as a movable member. In that case, the firsthousing 1 of the rotary connector is first fixed to a steering column.After a steering shaft is protruded from the shaft insertion hole 8 ofthe second housing 5, a steering hub is press-fitted with the steeringshaft and a steering wheel formed integrally with the steering hub isfixed to the second housing 5. Thereafter, an external connector mountedon a car body is connected to the special connector led out from thefirst housing 1, and an external connector mounted on the steering wheelis connected to the direct connector 10 provided on the second housing5, whereby an inflator for an air bag, a horn switch or control switchesof an automatic cruise circuit or air conditioner circuit, mounted onthe steering wheel, are connected to corresponding circuits mounted onthe car body through the rotary connector.

In the above-described arrangement, when the steering wheel is rotatedclockwise or counterclockwise, the rotational force of the steeringwheel is transmitted to the second housing 5, rotating the secondhousing 5 in the same direction as that in which the steering wheel isrotated. For example, when the steering wheel is rotatedcounterclockwise from a neutral rotation position, the second housing 5also rotates counterclockwise together with the steering wheel, makingthe flexible cable 9 wind toward the inner cylindrical portion 7.Conversely, when the steering wheel is rotated clockwise, the secondhousing 5 also rotates clockwise together with the steering wheel,making the flexible cable 9 unwind toward the outer cylindrical portion3. In either state, electrical connection between the housings 1 and 5is maintained through the flexible cable 9.

In the above-described first embodiment, at the connection portionbetween the flexible cable 9 and the direct connector 10, the individualconductor wires 11a to 11f of the flexible cable 9 are divided into theair bag conductors 11a and 11b and the other conductor wires 11c to 11f,and the terminals 14a to 14f of the direct connector 10, respectivelyconnected to the conductor wires 11a to 11f, are divided into the airbag terminals 14a and 14f and the other terminals 14c to 14f by theinsulating partitioning wall 13a. Thus, the conductors and terminals forthe air bag circuit, which require high connection reliability, can bereliably insulated electrically from the conductors and terminals of theother circuits. When electrical insulation of the conductors andterminals of the air bag circuit from the conductors and terminals ofthe other circuits can be conducted reliably, short-circuiting, whichwould occur between the other circuits due to the current which flows inthe air bag circuit into the other circuits, can be prevented.Accordingly, the pitch at which the conductors 11c to 11f used forconnection with the circuits other than the air bag circuit can bereduced, and even when the number of conductor wires 11c to 11f isincreased, a great increase in the width of the flexible cable 9 canthus be avoided. Further, since the conductor wire 11f located farthestfrom the air bag conductors 11a and 11b is used for connection with thehorn circuit, the insulation distance between the air bag circuit inwhich a largest amount of current flows and the horn circuit in which asecond largest amount of current flows can be increased, thus enhancingelectrical insulation of the air bag circuit. Further, since theflexible cable 9 is divided into the air bag conductors 11a and 11b andthe conductor wires 11c to 11f for the circuits other than the air bagcircuit at an end portion of the cable, the exposed ends of the air bagconductors 11a and 11b alone are dipped into a plating tank with theother conductor wires 11c to 11f on which expensive noble metal platingis conducted being not plated. Consequently, production cost can bereduced.

FIG. 4 is a perspective view of essential parts illustrating aconnecting state between the direct connector and the flexible cableprovided in the rotary connector according to a second embodiment of thepresent invention. Reference numerals in FIG. 4 identical to those inFIGS. 1 to 3 represent similar or identical elements.

The second embodiment differs from the first embodiment in that thefirst and second flexible cables 17a and 17b are employed and in thatthe air bag conductors 11a and 11b are provided on the first flexiblecable 17a while the other conductor wires 11c to 11f are provided on thesecond flexible cable 17b. The other structure of the second embodimentis the same as that of the first embodiment. That is, the two flexiblecables 17a and 17b are wound in the annular space in a state whereinthey are placed on top of the other in the direction of thicknessthereof over the entire length thereof. At least one end portions of theconductor wires 11a to 11f are connected to the corresponding terminals14a to 14f of the direct connector 10.

In the second embodiment, since the air bag conductors 11a and 11b andthe conductors 11c to 11f for the circuits other than the air bagcircuit are allocated to the first and second flexible cables 17a and17b placed on top of the other in the direction of thickness thereof,respectively, insulation between the air bag conductors 11a and 11b andthe conductor wires 11c to 11f for the circuits other than the air bagcircuit can be enhanced by the insulating films of the flexible cables17a and 17b and the width of the flexible cables 17a and 17b can benarrowed. Thus, the second embodiment is suited to achieve a reductionin the thickness of the rotary connector in addition to the effectsoffered by the first embodiment.

FIG. 5 is a perspective view of essential parts illustrating a connectedstate between the direct connector and the flexible cables provided inthe rotary connector according to a third embodiment of the presentinvention. Reference numerals in FIG. 5 identical to those in FIG. 4represent similar or identical elements.

The third embodiment according to the present invention differs from thesecond embodiment in that the terminals of the direct connector 10 aredivided into the air bag terminals 14a and 14b and the terminals 14c to14f for the circuits other than the air bag circuit in the direction ofthickness of the two flexible cables 17a and 17b through thepartitioning wall 13a. The other structure is the same as that of thesecond embodiment.

FIG. 6 is a perspective view of essential parts illustrating a connectedstate between the direct connector and the flexible cable provided inthe rotary connector according to a fourth embodiment of the presentinvention. Reference numerals in FIG. 6 identical to those in FIG. 4represent similar or identical elements.

The fourth embodiment differs from the second embodiment in that the airbag terminals 14a and 14b are separated from the terminals 14c to 14ffor the circuits other than the air bag circuit by a gap 18. The otherstructure of the fourth embodiment is basically the same as that of thesecond embodiment. The gap 18 is set to a value sufficiently large ascompared with the pitch (spacing) between the air bag terminals 14a and14b or the pitch between the other., terminals 14c to 14f, and has thesame function as that of the partitioning wall 13a which has beendescribed in the first to third embodiments.

There is no limitation to the shape of the partitioning wall 13aemployed in the first to third embodiments so long as the creepagedistance for insulation between the air bag terminals 14a and 14b andthe terminals 14c to 14f for the circuits other than the air bag circuitis long.

While the above embodiments are shown in FIGS. 1 to 6, wherein the firsthousing 1 is used as the fixing member and the second housing 5 is usedas the movable member, other embodiments of the invention might includea rotary connector wherein the second housing 5 is used as the fixingmember and the first housing 1 is used as the movable member.

Similarly, while the direct coupling type direct connector 10 isprovided only on the second housing 5 while the special connector to beled out of the housing is provided on the first housing 1, alternateembodiments might contemplate a rotary connector in which the directconnector is provided only on the first housing while the specialconnector is provided on the second housing 5 and a rotary connector inwhich direct coupling type connectors are provided on both the housings1 and 5.

A second aspect of the present invention will be described withreference to FIGS. 7-9.

FIG. 7 is a perspective view of a rotary connector according to a fifthembodiment of the present invention. FIG. 8 is a verticalcross-sectional view illustrating a state wherein a locking member ismounted on the rotary connector. In these figures, a first housing 101made of a synthetic resin has a disk-shaped bottom plate 102 and anouter cylindrical portion 103 erected from an outer peripheral edge ofthe bottom plate 102. The bottom plate 102 has a center hole 104 formedat a center thereof. A second housing 105, made of a synthetic resin,has a disk-shaped ceiling plate 106 and an inner cylindrical portion 107connected to a central portion of the ceiling plate 106. The innercylindrical portion 107 has a shaft insertion hole 108. The first andsecond housings 101 and 105 are coupled to each other in such a manneras to be rotatable relative to each other with the outer peripheral edgeof the ceiling plate 106 being guided by the upper edge of the outercylindrical portion 103 while the lower edge of the inner cylindricalportion 107 being guided by the inner edge of the bottom plate 102.However, free rotation of the first and second housings 101 and 105 isprohibited by a locking member which will be described later. A flexiblecable 109 is a belt-like flat cable in which a plurality of parallelconductor wires are laminated by a pair of insulating films. Theflexible cable 109 is housed in an annular space defined by the bottomplate 102 and outer cylindrical portion 103 of the first housing 101 andthe ceiling plate 106 and the inner cylindrical portion 107 of thesecond housing 105. The flexible cable 109 is wound in a spiral fashionin the space. One end of the flexible cable 109 is led out from thefirst housing 101 in a state wherein it is fixed to the outercylindrical portion 103. A special connector 110 is connected to adistal end of the portion of the flexible cable 109 which is led outfrom the first housing 101. The other end of the flexible cable 109 isled out of the second housing 105 through a direct-coupling typeconnector 111 erected from the upper surface of the ceiling plate 106.The direct connector 111 includes a plurality of terminals 111aconnected to the respective conductors of the flexible cable 109, and aprotruding casing 111b for enclosing the terminals 111a. The terminals111a are exposed through an upper opening of the protruding casing 111b.

A locking member 112 includes a box-shaped cover 112a which is open atan under surface thereof, a knob portion 112b protruding upward from thecover 112a, and an arm 112c extending horizontally from a side surfaceof the cover 112a. The locking member 112 is a one-unit member made of asynthetic resin or hard rubber. The cover 112a has an inner space largeenough to cover the protruding casing 111b of the connector 111. Adistal end portion of the arm 112c has a hole 112d. Corresponsive to thelocking member 112, a protrusion 113 is formed integrally with the outercylindrical portion 103 of the first housing 101 at an outer peripheralsurface thereof. The protrusion 113 has a boss 114 on an upper surfacethereof. In addition, thin portions 113a are formed at a connectingportion between the outer peripheral surface of the outer cylindricalportion 103 and the protrusion 113. The thin portions 113a have thefunction of rupture portions when the protrusion 113 is removed from thefirst housing 101.

FIG. 7 illustrates a non-locked state wherein the locking member 112 isnot yet mounted on the rotary connector. FIG. 8 illustrates a lockedstate wherein the locking member 112 is mounted on the rotary connector.In that locked state, the cover 112a of the locking member 112 iscovered on the protruding casing 111b of the connector 111, and fixed tothe protrusion 113 by heat caulking the hole 112d of the arm 112c to theboss 114.

The operation of the rotary connector according to the present inventionwill now be discussed. In the following description, the first housing101 is used as a fixing member, while the second housing 105 is used asa movable member. In that case, the first housing 101 of the rotaryconnector is fixed to a steering column, and the second housing 105 isfixed to a steering wheel. Such a rotary member must be assembled in asteering device in such a manner that the second housing 105 serving asthe movable member can be rotated by the same angle from the rotationneutral position of the steering wheel in two directions. To achievethis, in the manufacturing process of the rotary connector, after thefirst and second housings 101 and 105 are rotatably coupled to eachother in a state wherein the flexible cable 109 is wound in the space,they are rendered to a neutral rotation state, as shown in FIG. 7.Thereafter, as shown in FIG. 8, the cover 112a of the locking member 112is covered on the direct connector 111 of the second housing 105 and thehole 112d of the arm 112c is fitted with the boss 114. In that state,the boss 114 is heat caulked to fix the arm 112c to the protrusion 113of the first housing 101. Thus, even if a rotational force is applied tothe second housing 105, relative rotation of the first and secondhousings 101 and 105 could be prevented by the locking member 112because the protruding casing 111b of the direct connector 111 abutsagainst a restriction wall of the cover 112a located in the direction ofrotation of the protruding casing 111b. Consequently, even if vibrationsact on the rotary connector during, for example, transportation, removalof the locking member 112 from the rotary connector would be preventeddue to heat caulking of the boss 114. This enables the rotary connectorto be assembled in the steering device in the neutral rotation state.

To assemble the rotary connector in the steering device (not shown), thefirst housing 101 of the rotary connector with the locking member 112mounted thereon is fixed to the steering column, and a steering shaft isprotruded from the shaft insertion hole 108 of the second housing 105.Next, the operator grips the knob portion 112b with a jig or his or herfingers and pulls up the locking member 112. In the pulling process, thethin portions 113a rupture and the protrusion 113 fixed to the arm 112cis separated from the first housing 101. Thus, removal of the lockingmember 112 from the rotary connector is facilitated, and at the sametime, the cover 112a can be removed from the direct connector 111.Thereafter, a steering hub is press-fitted on the steering shaft, and asteering wheel provided integrally with the steering hub is fixed to thesecond housing 105, whereby the neutral rotation position of the rotaryconnector can be brought into coincidence with the neutral rotationposition of the steering wheel. A connector 110 led out of the firsthousing 101 through the flexible cable 109 is connected to an externaldevice, such as an air bag driving circuit or a horn circuit, mounted onthe car body, and the connector 111 provided on the second housing 105is connected to an external device, such as an air bag inflator or ahorn switch, mounted on the steering wheel.

When assembly of the rotary connector in the steering device iscompleted, inspection is conducted to check whether or not the rotaryconnector is connected accurately to the external devices. In thisinspection in which electrical connection between the correspondingexternal devices is checked, if electrical characteristics aresatisfactory, electrical connection between the rotary connector and theexternal devices are determined as satisfactory and the locking member112 are determined as removed from the rotary connector That is, sincethis embodiment is designed such that the external devices can beconnected to the direct connector 111 only when the cover 112a formedintegrally with the locking member 112 has been removed, whether or notthe locking member 112 has been removed can be determined by inspectingelectrical connection between the rotary connector and the externaldevices, and production of defective articles due to the locking member112 being accidentally left on the rotary connector can thus beprevented.

In the above-described arrangement, when the steering wheel is rotatedclockwise or counterclockwise, the rotational force of the steeringwheel is transmitted to the second housing 105, rotating the secondhousing 105 in the same direction as that in which the steering wheel isrotated. For example, when the steering wheel is rotatedcounterclockwise from a rotation neutral position, the second housing105 also rotates counterclockwise together with the steering wheel,making the flexible cable 109 wind toward the inner cylindrical portion107. Conversely, when the steering wheel is rotated clockwise, thesecond housing 105 also rotates clockwise together with the steeringwheel, making the flexible cable 199 unwind toward the outer cylindricalportion 103. In either state, electrical connection between the housings101 and 105 is maintained through the flexible cable 109.

In the fifth embodiment of the invention, since the cover 112a forprotecting the direct connector 111 of the second housing 105 is formedintegrally with the locking member 112 for inhibiting free rotation ofthe housings 101 and 105, protection of the direct connector 111 can beachieved when the locking member 112 is mounted on the rotary connector.Thus, it is not necessary for the direct connector 111 to be coveredwith a covering member, facilitating the assembly operation.Furthermore, since the cover 112a has the restriction wall which abutsagainst the protruding casing 111b of the direct connector 111 in thedirection of rotation thereof, that is, since the direct connector 111constitutes part of the locking mechanism, it is not necessary for thesecond housing 105 to be provided with a rotation stopping member whichis to abut against the locking member 112, simplifying the lockingmechanism. Furthermore, since the locking member 112 is fixed to theprotrusion 113 of the first housing 101 to prevent slip off of thelocking member 112 from the rotary connector, it is not necessary forthe cover 112a to be mounted tightly on the direct connector 111, thussimplifying mounting and removal of the cover 112a.

FIG. 9 is a perspective view of essential parts of the rotary connectoraccording to a sixth embodiment of the present invention. Referencenumerals in FIG. 9 identical to those in FIGS. 7 and 8 represent similaror identical elements.

The sixth embodiment of the invention differs from the fifth embodimentin that the cover 112a of the locking member 112 is shaped in the formof a flat plate and in that a pair of restricting pins 115 are erectedon the second housing 105 as rotation stopping members of the lockingmember 112. The other structure of the sixth embodiment is the same asthat of the fifth embodiment. In that case, although the cover 112a hasonly the protection function of covering the upper opening of theconnector 111, since the arm 112c abuts against the restriction pins 115in the direction of rotation of the second housing 105, relativerotation of the first and second housings 101 and 105 is prohibited bythe locking member 112. In that case, the simple structure of therestriction pins 115 is enough to prevent relative rotation of the firstand second housings 101 and 105.

While the fifth and sixth embodiments of the invention are substantiallyshown in FIGS. 7 to 9, wherein the first housing 101 acts as the fixingmember while the second housing 105 serves as the movable member,alternate embodiments of the invention might include a rotary connectorwherein the second housing 105 serves as the fixing member and the firsthousing 101 serves as the movable member.

Similarly, the direct coupling type direct connector 111 is shown in thefifth and sixth embodiment as being provided only on the second housing105 with the externally extending connector 110 provided on the firsthousing 101, alternate embodiments might contemplate a rotary connectorwherein the connectors which are to be provided on both the housings 101and 105 are direct connectors and a rotary connector wherein one end ofthe locking member is fixed to the second housing 105 with the directconnector covered with a cover being provided on the first housing 101.

Similarly, while the locking member 112 is shown in the fifth and sixthembodiments as being fixed to the protrusion 113 by heat caulking theboss 114 which has been fitted with the hole 112d formed in the lockingmember 112, alternate embodiments might include the locking member 112that is fixed to the protrusion 113 by merely press-fitting the boss 114into the hole 112d to simplify the process and thereby facilitate theassembly operation. Alternatively, the locking member 112 may have aboss with the protrusion 113 having a hole, unlike the cases of theabove-described embodiments. Similarly, while the thin portions 113a areshown in the fifth and sixth embodiments as being provided at theproximal end of the protrusion 113, alternate embodiments of theinvention might include thin portions that are provided at a breakingpoint of the locking member 112 alone or that are provided on both thelocking member 112 and the protrusion 13.

As will be understood from the foregoing description, in the presentinvention, even though the number of conductors of the flexible cableand the number of terminals of the direct connector which are connectedto the respective conductors are increased, the air bag conductor andthe terminal connected thereto are electrically insulated reliably fromthe other conductors and terminals, thus making the provision of arotary connector suitable for use with multiple circuits possible.

Furthermore, in the present invention, since the locking member ismounted relative to the both housings which have been positioned to aneutral rotation position in the manufacturing process of the rotaryconnector, free rotation of the housings is locked and the directconnector provided on the housing is protected, thus simplifying theassembly operation. Further, when the locking member is removed from thetwo housings in the process of assembly of the rotary connector in asteering device, the two housings are unlocked while the cover isremoved from the direct connector. Thus, whether or not the lockingmember has been removed can be determined by inspecting electricalconnection between the rotary connector and external devices, and thelocking member being accidentally left on the rotary connector can bereliably prevented.

What is claimed is:
 1. A rotary connector comprising:a first housing; asecond housing rotatably coupled to the first housing, the first andsecond housings defining an annular space therebetween; and a flexiblecable wound in the annular space, said flexible cable including aplurality of parallel conductors, first and second ends of said flexiblecable being electrically connected to an exterior of the first andsecond housings such that the first and second ends of said flexiblecable are fixed to said first and second housings, respectively at leastone of said first and second extending ends of said flexible cable beingconnected to an external device through a direct connector provided onone of said first and second housings, a locking member removablyconnected to the first and second housings for prohibiting relativerotation between said first and second housings, wherein a cover forcovering said direct connector is formed integrally with said lockingmember.
 2. A rotary connector according to claim 1, wherein said coverincludes a restriction wall which receives the direct connector suchthat the restriction wall opposes relative rotation of said first andsecond housings.
 3. A rotary connector according to claim 1, wherein oneof said first and second housings on which said direct connectorincludes a restriction protrusion which abuts a portion of the lockingmember and thereby opposes relative rotation of said first and secondhousings.